Ok seriously
Just to give you some facts. R-12 Transfers heat 20% better than 134a. This means that if you run 134a in you car, you'll need to upgrade the btu of the condenser to take away the heat to the outside of your car better. See the key here when talking A/C is that it doesn't primarily cool. Rather, it takes the heat from the inside of the car via the evaporator, and transfers it to the outside of the car, were it loses its heat through the condenser. The cold air blowing on you is just a byproduct of the heat taken away.
What you'll need to do to make it run "cool" is run a condenser with at least 20% more efficiency then the one you got now. What the manufactures of Air-conditioning have done, is slow down the flow of 134a through condenser reconfiguration. They threw away the old series flow condensers and made them flow in parallel. What they call Para flow. Slowing down the flow of Freon allowed the outside air time to extract the heat from the condenser.
You should never run a used condenser. Why would you want to get used junk and put it in your car? Through age, heat and other types of wear, your compressor spits out little parts into the condenser. These parts start to lodge in your current series flowing condenser hampering its ability to lose its heat. Every and all compressors do this, and in our older type of condensers reverse flushing doesn't guaranty a thorough flowing unit.
Anyway Cale, you’re a rich kid just do the job correct the first time and be done with it. Which means Change your hoses to the barrier type, your condenser to the para-flow kind and convert it to 134a. Some of the mechanics theories are partly true in regards to R-12 and it’s cooling, but when you hop in your Honda, Caddy or what have you. How can you say they run 20% warmer than before? And if you don’t convert your system properly just based on economics, do it for Mother Nature and our o-zone.